Hudson authorities said a UPS driver found Chad Wang of Spring Valley, Minn., semi-conscious on the floor Friday afternoon. The 35-year-old was lying in a pool of blood.

Police said Saturday the injury was apparently the result of an accidental explosion. They said Wang was using an acetylene torch to open the sealed drum, which had a small volume of oil inside. An explosion caused the lid to shoot upward and hit him in the head.

Authorities said Wang may have been on the floor for as long as several hours before he was found.